Album and event contents jumbled on iOS devices when synced with iPhoto

I sync my whole iPhoto library with my iPad, and selected events with my iPhone. within the last few weeks, all albums and events on these devices show completely the wrong photos - not just the wrong order or some missing, but a random collection of photos from all over my library (they do, however, contain the correct number of photos). The albums aand events are all fine in iPhoto itself.

I've tried every option in the advanced startup mode of iPhoto (rebuild, rebuild from backup, rebuild thumbs, etc). I've also tried removing all photos from the iOS devices, then re-adding them.

The odd behaviour happened shortly after upgrading to iPHoto '11, and also after migrating my library to a new machine.

Has anyone had this behaviour, and solved it? Or have any suggestions?